Degradation of hypoxanthine guanine phosphoribosyl transferase in Chinese hamster ovary cells

Author

Richard Machanoff

Date of Award

3-1982

Degree Type

Thesis

Degree Name

Master of Science

Major Professor

F. T. Kenney

Committee Members

P. Lalley, J. P. O'Neill, R. J.

Abstract

In the study of mammalian somatic cell genetics, the Chinese hamster ovary cell/hypoxanthine guanine phosphoribosyl transferase (CHO/HGPRT) assay has demonstrated that mutation fixation and mutant induction are temporally separate from the expression of mutant phenotype, implicating metabolic turnover of gene products (mRNA and protein) in phenotypic expression. This specific locus mutation assay selects mutants with the phenotype of resistance to 6-thioguanine, a result of deficient or altered HGPRT. A delay of several days in the expression of mutant phenotype is observed when mutagenized cultures are either growth-arrested or grown continuously.

These observations were investigated in this study, where the contribution of intracellular HGPRT degradation to the expression of mutant phenotype was examined in growing and arrested CHO cells. This was done by an isotopic "label and chase" treatment of cultures followed by immunochemical purification and SDS-urea-PAGE analysis. First order rates of degradation were measured for HGPRT in growing and arrested cells. The effects of intracellular protein degradation, dilution by cell division and metabolic turnover of mRNA are discussed, in relation to phenotypic delay and intracellular HGPRT activity.

Recommended Citation

Machanoff, Richard, "Degradation of hypoxanthine guanine phosphoribosyl transferase in Chinese hamster ovary cells. " Master's Thesis, University of Tennessee, 1982.
https://trace.tennessee.edu/utk_gradthes/15054